git diff --staged for staged changes - Mini Project: Build & Apply

Using git diff --staged to View Staged Changes

📖 Scenario: You are working on a small project and have made some changes to your files. Before committing, you want to see exactly what changes you have staged for the next commit.

🎯 Goal: Learn how to use git diff --staged to view the changes that are currently staged in Git.

📋 What You'll Learn

Have a Git repository initialized

Have at least one file modified and staged

Use git diff --staged to view staged changes

💡 Why This Matters

🌍 Real World

Developers often want to review what changes they have prepared to commit. Using <code>git diff --staged</code> helps them see exactly what will be included in the next commit.

💼 Career

Understanding how to view staged changes is essential for software developers and DevOps engineers to ensure code quality and proper version control before sharing code with others.

1

Initialize a Git repository and create a file

Initialize a Git repository in the current folder by running git init. Then create a file named example.txt with the exact content Hello World.

Git

# Run git init and create example.txt with content 'Hello World'
# Your code here

Hint

Use git init to start a new repository. Use echo "Hello World" > example.txt to create the file with content.

2

Stage and commit the initial file

Stage the file example.txt by running git add example.txt and commit it using git commit -m "Initial commit".

Git

git init

echo "Hello World" > example.txt
# Stage example.txt using git add and commit it
# Your code here

Hint

Use git add example.txt to stage the file, then git commit -m "Initial commit" to commit it.

3

Modify the file and stage the changes

Change the content of example.txt to Hello Git and stage the changes again with git add example.txt.

Git

git init

echo "Hello World" > example.txt
git add example.txt
git commit -m "Initial commit"
# Change content of example.txt to 'Hello Git' and stage it
# Your code here

Hint

Use echo "Hello Git" > example.txt to overwrite the file and then stage it again.

4

View the staged changes using git diff --staged

Run git diff --staged to display the changes that are currently staged for commit.

Git

git init

echo "Hello World" > example.txt
git add example.txt
git commit -m "Initial commit"
echo "Hello Git" > example.txt
git add example.txt
# Run git diff --staged to see staged changes
# Your code here

Hint

The output should show the line removed -Hello World and the line added +Hello Git.

Practice

1. What does the command git diff --staged show?

easy

A. Changes that are staged and ready to be committed

B. All changes in the working directory, staged or not

C. The commit history of the repository

D. Untracked files in the repository

Solution

1. Step 1: Understand what staging means in Git

   Staging means preparing changes to be saved in the next commit.

2. Step 2: Identify what git diff --staged compares

   This command compares the staged changes against the last commit, showing what will be committed.

3. Final Answer:

   Changes that are staged and ready to be committed -> Option A

4. Quick Check:

   Staged changes = git diff --staged output [OK]

Hint: Remember: --staged shows only prepared changes [OK]

Common Mistakes:

• Confusing staged changes with all changes
• Thinking it shows commit history
• Assuming it lists untracked files

2. Which of the following is the correct syntax to view staged changes using git?

easy

A. git diff staged

B. git diff --cached

C. git diff --stage

D. git diff --status

Solution

1. Step 1: Recall git diff options for staged changes

   Git uses --cached as the official option to show staged changes.

2. Step 2: Understand that --staged is an alias

   --staged is a common alias but --cached is the correct and original syntax.

3. Final Answer:

   git diff --cached -> Option B

4. Quick Check:

   Correct syntax for staged diff = git diff --cached [OK]

Hint: Use --cached to view staged changes reliably [OK]

Common Mistakes:

• Using incorrect flags like --stage
• Omitting the double dash before options
• Confusing staged with unstaged flags

3. Given the following commands executed in order:

echo 'Hello' > file.txt
git add file.txt
git diff --staged

What will git diff --staged display?

medium

A. No output, because the file is new and staged

B. An error because the file is not committed yet

C. The difference showing removal of 'Hello' in file.txt

D. The difference showing the addition of 'Hello' in file.txt

Solution

1. Step 1: Understand the state of file.txt after commands

   The file is new with content 'Hello' and has been staged with git add.

2. Step 2: What does git diff --staged show here?

   It shows the difference between the staged version and the last commit (which has no file.txt), so it shows the addition of 'Hello'.

3. Final Answer:

   The difference showing the addition of 'Hello' in file.txt -> Option D

4. Quick Check:

   New staged file diff shows added content [OK]

Hint: New staged files show additions in git diff --staged [OK]

Common Mistakes:

• Expecting no output for new files
• Thinking git diff --staged errors on new files
• Confusing removal with addition

4. You modified files in your editor, staged them with git add, ran git diff --staged but saw no output. What could be the problem?

medium

A. You staged the files but forgot to save changes in the editor

B. You used git diff instead of git diff --staged

C. You committed the changes already, so no staged changes remain

D. The repository has no commits yet

Solution

1. Step 1: Check if file changes are saved before staging

   If changes are not saved in the editor, staging old content means no visible diff.

2. Step 2: Understand why no output appears

   Since staged content matches last commit (or is empty), git diff --staged shows nothing.

3. Final Answer:

   You staged the files but forgot to save changes in the editor -> Option A

4. Quick Check:

   Unsaved edits cause empty staged diff [OK]

Hint: Always save files before staging to see diffs [OK]

Common Mistakes:

• Assuming git diff --staged shows unstaged changes
• Not realizing files were not saved
• Thinking commit status affects staged diff output

5. You have staged changes in two files: app.js and index.html. You want to see only the staged changes in app.js. Which command should you use?

hard

A. git diff --cached index.html

B. git diff app.js staged

C. git diff --staged app.js

D. git diff --staged --name-only app.js

Solution

1. Step 1: Understand how to limit git diff to a specific file

   You can specify the file path after the options to filter the diff output.

2. Step 2: Choose the correct syntax for staged changes and file filter

   git diff --staged app.js correctly shows staged changes only for app.js.

3. Final Answer:

   git diff --staged app.js -> Option C

4. Quick Check:

   File filter after --staged shows staged diff for that file [OK]

Hint: Put filename after --staged to filter staged diff [OK]

Common Mistakes:

• Placing filename before options
• Using --name-only which lists files, not diffs
• Mixing staged and unstaged file filters